ODNR geologists posted new maps on the agency’s website last week after reviewing information from 100 new locations.

The revised map supports earlier speculation that eastern Ohio — including Stark, Carroll and Tuscarawas counties — should be a hot spot for oil and liquid natural-gas production. But it extends potential production farther west and south.

In particular is a projected hot spot that straddles Marion and Wyandot counties. A map released last year indicated there might be fair to good production in parts of Marion, Delaware and Union counties. The revised map indicates good to very good production in those areas, as well as in Hancock, Hardin, Wyandot and Seneca counties.

NEW DATA

Geologists used information from wells drilled this past year, as well as core samplings and cuttings from test wells. The samples measure the total organic carbon in the rock. Measurements indicate how much oil and natural gas might be found.

Companies have volunteered the information to ODNR, spokesman Matt Eiselstein said. This year, the state has more information from samples collected in western counties.

Those samples have “more or less brought that into clearer focus,” Eiselstein said of the western counties.

The Utica shale is a source rock for oil and natural gas, said Pete MacKenzie, a geologist and vice president of operations for the Ohio Oil & Gas Association. Oil and gas moves from the shale and collects in other rock formations. During the past 10 years, however, companies have started drilling shale to extract hydrocarbons.

LIKELY TO CHANGE

Companies have been aware of the Utica shale formation, which lies under most of Ohio, for many years, said Rhonda Reda, executive director for the Ohio Oil and Gas Energy Education Program.

“The questions have been how thick that rock is, how organic,” Reda said. Companies try to drill in thicker shale formations.

MacKenzie said the state’s new map represents what state geologists believe is happening in the Utica formation. ODNR’s map is one of several developed in an effort to guess what might be going on thousands of feet below the surface.

“It’s reflecting what the companies are seeing with the drill bit,” MacKenzie said of the information.

As more wells are drilled, more information will be collected. Right now, the map is based on data collected at specific points, but there are many miles separating those points. It’s likely the map will change again, MacKenzie said.

ODNR will update its maps as it gets more information, Eiselstein said.